1. Field of the Invention
The invention relates to a method for the wet separation of acidic impurities from gases containing the same which gases are to be scrubbed at an elevated temperature, preferably above 575.degree. K.
2. Description of the Prior Art
In various industrial processes, gases containing acidic constituents as impurities, for example sulfur dioxide, are produced. Considerable effort has been directed to this problem but improvement is yet required particularly in scrubbing gases at high temperatures above about 600.degree. K.
It is known to use, metal melts such as, for instance, melts of tin or tin-containing alloys (German Published Prosecuted Application DE-AS 26 05 249) for scrubbing gases which have no oxidizing properties and which are to be scrubbed at an elevated temperature, for instance, above 575.degree. K. It is also known to carry out such scrubbing methods with salt melts (Battelle Study R&D Report 100, entitled "A process for cleaning and removal of sulfur compound from low-BTU gases", Washington, August 1974). According to this investigation, a solution of calcium carbonate in a molten eutectic mixture of potassium carbonate, sodium carbonate and lithium carbonate is used as the washing fluid. The operating range of this mixture is at temperatures above about 875.degree. K. According to this investigation, gas with temperatures above 800.degree. C., was so purified. This is a temperature range in which difficulties in separating them from the scrubbed gas can be expected due to the elevated vapor pressures of the alkali salts. Since lithium salts are used in this mixture, the costs of this melt are high. Due to these high costs of the raw material, it is necessary to reprocess the melts used. According to the Battelle study, this requires considerable expenditures and it is unclear, at least up to now, whether a melt containing the separated impurities can be reprocessed at all economically. In any event, the cost burden due to the gas scrubbing according to the Battelle study, which is determined by the continuous consumption of salts and salt mixtures and by the disposal costs, is so high that economical utilization is questionable.